From Uncommon Infection to Multi-Cranial Palsy: Malignant External Otitis Insights

Purpose: The progression of the otitic infectious process toward diseases of particular severity is often unpredictable, just as it is challenging to manage the patient over time, even after the apparent resolution of the disease. We aim to define a radiological reading key that allows us to correctly and promptly treat the disease, avoiding the possible severe complications. Methods: We conducted a retrospective study of 13 cases of basal cranial osteomyelitis (SBO) due to malignant external otitis, by the ENT Department of the University of Catania. Through a standardized approach and following the latest guidelines, we have evaluated all patients performing a standardized and personalized radiological protocol according to the stage of the patient’s pathology and modulating the treatment consequently. Results: Clinical signs have been observed such as otorrhea (100%), otalgia in 13/13 patients (100%), granulations in external auditory canal (100%), preauricular cellulitis in 9/13 patients (69%) headache 6/13 cases (46%), dysphonia 4/13 cases (31%). HRCT of the temporal bone proved useful in identifying even minimal bone lesions in 13/13 (100%) while improving MRI in vascular and nervous involvement, although in 1/13 patient with nerve palsy clinical symptomatology preceded radiological evidence. The 99mTc 3-phase planar bone scintigraphy was positive for SBO in 9/13 cases (69%) during the initial phase and, in 100% of the cases in images delayed to 2-3 hours. Subsequent checks up to 1 year, using the Ga 67 scintigraphy, excluded the presence of recurrences in 100% of patients. Conclusion: The osteomyelitis of the base of the skull is a severe complication of malignant external otitis, often not always easily diagnosed. Recurrence can occur up to 1 year after stopping therapy. Imaging techniques such as Tc and MRI are relevant for the initial diagnostic approach and the staging of the pathology and its complications. Nuclear medicine imaging plays a fundamental role in the evaluation of related osteoblastic activity, especially in the remission phase of the disease.